class_docstr: Defines a dataset composed of Examples along with its Fields.
  
  Attributes:
      sort_key (callable): A key to use for sorting dataset examples for batching
          together examples with similar lengths to minimize padding.
      examples (list(Example)): The examples in this dataset.
      fields (dict[str, Field]): Contains the name of each column or field, together
          with the corresponding Field object. Two fields with the same Field object
          will have a shared vocabulary.
code: def __iter__(self):
      for x in self.examples:
          yield x
  
imports: import csv
  import gzip
  import io
  import os
  import shutil
  import tarfile
  import zipfile
  from functools import partial
  import torch.utils.data
  from torchtext.data.utils import RandomShuffler
  from torchtext.utils import download_from_url
  from .example import Example
label_desc: Use image node_id 6 for calling the Dataset obj's underlying member method code with example usage: obj.__iter__() without return types